Abstract
Purpose :
The aim of this study is to analyse the evolution of classical topographic objective parameters (thinnest pachymetry (TP), maximal anterior curvature (Kmax) and astigmatism evolution) during a 2-year long follow up after A-CXL procedure, and evaluate their pertinence in keratoconus progression evaluation.
Methods :
All consecutive patients treated with A-CXL between march 2014 and November 2016, who had at least a 2 year long follow up were included. They all underwent the same procedure: accelerated-CXL protocole (De-epithelialization, 30 minutes Riboflavin impregnation followed by 10 minutes UVA irradiation at 9 mW/cm2 intensity). Irradiation device : IROC UV-X™ 2000, Medeuronet. The indication of all these CXL was a progressive keratoconus. A corneotopography (Sirius SCHWIND, Scheimpflug camera) was performed, before A-CXL procedure 6 months, one and two years after A-CXL.
Keratoconus progression was defined by presenting at least one of the following modifications : Kmax progression of 1D, 1D of astigmatism measured at 5 mm of central cornea or a 10 percent thinning of the thinnest point.
A progression rate was calculated at 6 months, one year, and two years, defined as the proportion of eyes presenting a progression in at least one of this items.
Results :
85 eyes who underwent A-CXL procedure were included.
Mean age was 24(SD=7 ) years. 33 % were female. Mean minimal pachymetry was measured at 456(preoperative) 428(M6), 430(Y1) and 440(Y2). Mean Kmax was 56.9D(preoperative) 56.8D(M6), 57.3D(Y1) and 56.1D(Y2). Mean topographical astigmatism at 5 millimeters was -2.94D(preoperative), -3.05D(6M) , -2.79(Y1) and -2.35(Y2).
The calculated progression rates were found to be 42,4% at 6 months, 54,5% at one year and 30,3% at two years.
Conclusions :
It seems important not to judge the evolutivity of a keratoconus too early after an A-CXL procedure. Indeed our study shows a temporary aggravation of keratoconus classical evolution markers at 6 months and one year, that spontaneously improves at 2 years. Many eyes would have been misclassified as progressing keratoconus. It appears senseful to wait more than one year after CXL procedure before deciding to repeat the treatment.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.